I have three G-Drives, 2x 2TB and 1 4TB, these are daisy chained with FW800 to my iMac.

Randomly they unmount, sometimes after a few hours and sometimes even after 30 min. 9 out of 10 times this happens when the computer has been put to sleep. In the energy saver in system preferences, i unchecked to put the hard drives to sleep.I used different FW800 cables, switched the order in the daisy chain, but nothing seems to help.

Personally i think the drives are ok, but something in the OSX is making this happening. Up to OSX 10.6 i never had this problem, could be coincidence but it seemed to me it started after upgrading to 10.7 and 10.8.

Thanks for your post. You mention that it did not exhibit this issue on 10.6, did you have all the drives at that time? Do the drives have the issue when connected alone? Using Keep Drive Spinning or another called Disksomnia are effective in keeping drives awake, and the drives are kept available. It should not affect performance or durability. Please let m,e know if you have any questions.

Dear Gene,Thanks for your reply.I am certain thats it an OSX issue. Been testing all combinations, but that doesn't make any difference.

What occurs now it that all my HDD's are unmounting, even the USB ones.Strangely they mount and unmount randomly when the computer has been in sleep mode.Even my SD card which i unmounted, gives me an error that i didn't unmount the disc correctly after sleep modus and is then visible on my desktop.

So certainly it isn't to do with the G-Drive (thats one good thing Have to look for an OSX solution.